U.S. Pat. No. 4,912,011 discloses a light-sensitive material comprising a support and a light-sensitive layer provided thereon which contains silver halide, a reducing agent, a polymerizable compound and a color image forming substance. The silver halide, the reducing agent, the polymerizable compound and the color image forming substance are contained in microcapsules (light-sensitive microcapsules) which are dispersed in the light-sensitive layer.
U.S. Pat. No. 4,440,846, No. 4,483,912 and No. 4,554,235 disclose a light-sensitive material comprising a support and a light-sensitive layer provided thereon which contains a photopolymerization initiator, a polymerizable compound and a color image forming substance. The photopolymerization initiator, the polymerizable compound and the color image forming substance are contained in microcapsules (light-sensitive microcapsules) which are dispersed in the light-sensitive layer.
The above-mentioned light-sensitive microcapsules are usually prepared by a process comprising the steps of: emulsifying an oily phase (0) containing the silver halide, the reducing agent, the polymerizable compound and the color image forming substance (or an oily phase containing the photopolymerization initiator, the polymerizable compound and the color image forming substance) in an aqueous medium (W) containing a water-soluble polymer in water to prepare an aqueous emulsion (O/W); and forming the shell around the droplets of the oily phase. The oily phase containing a silver halide is prepared by emulsifying a silver halide emulsion (W) in an oily phase (O) containing the polymerizable compound to prepare an oily emulsion (W/O). The oily emulsion is further emulsified in an aqueous medium (W) containing a water-soluble polymer in water to prepare an aqueous emulsion (W/O/W).
The quality of the light-sensitive microcapsules depends on their particle sizes. The microcapsules preferably have a uniform particle size distribution as is described in U.S. Pat. No. 4,920,027. The microcapsules having a uniform particle size distribution are improved in the color density and are reduced in occurrence of stain.
In preparation of the aqueous emulsion (O/W or W/O/W), an emulsifying device having dispersing wings such as a homogenizer and a dissolver was used.